Air bag restraining systems in vehicles for vehicle occupants are known in the art. An air bag restraining device may include a multistage inflator where the stages are actuated at different times in response to vehicle crash conditions.
U.S. Pat. No. 5,935,182 to Foo et al., assigned to TRW Inc., discloses a method and apparatus for discriminating a vehicle crash condition using virtual sensing. U.S. Pat. No. 6,036,225 to Foo et al., assigned to TRW Inc., discloses a method and apparatus for controlling a multistage actuatable restraining system in a vehicle using crash severity index values. U.S. Pat. No. 6,186,539 to Foo et al., also assigned to TRW Inc., discloses a method and apparatus for controlling a multistage actuatable restraining device using crash severity indexing and crush-zone sensors. U.S. Pat. No. 6,529,810 to Foo et al., also assigned to TRW Inc., discloses a method and apparatus for controlling an actuatable multistage restraining device using several thresholds based on transverse acceleration.